Remove unneeded React.Component type parameters

TypeScript's new type parameter defaulting makes these unnecessary.

Author: pelotom

packages/react-scripts/template/src/App.tsx

@@ -3,7 +3,7 @@ import './App.css';
 
 const logo = require('./logo.svg');
 
-class App extends React.Component<{}, {}> {
+class App extends React.Component {
  render() {
  return (
  <div className="App">